using reserved words in R, and reuse variable names in different functions

See fortune("dog").
To wit:
  "Firstly, don't call your matrix 'matrix'. Would you call your dog 'dog'? Anyway, it might clash with the function 'matrix'"

I once had a cat named "kitty" and she never had a problem with it.

Clashes between non-functions and functions that cause problems are not that common.  With 4000 packages, each with a number of functions, it is hard to avoid using a name that someone has used for a function.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
Of Rolf Turner
Sent: Saturday, March 02, 2013 5:01 AM
To: Sarah Goslee
Cc: r-help
Subject: Re: [R] using reserved words in R, and reuse variable names in different
functions

On 03/02/2013 01:12 PM, Sarah Goslee wrote:
On Fri, Mar 1, 2013 at 7:06 PM, C W <tmrsg11 at gmail.com> wrote:
Thanks, that was just an example I came up with.  I was just curious if
using same variable names in different functions would cause problems.
No. The environment of a function is independent of other functions.

  Especially with reserved words.
Yes. Using reserved words can cause all kinds of subtle problems. Avoid it.

Very sound advice.  But it should be noted that "t", "c", and "matrix"
to which
the OP referred are *not* technically reserved words.  Nonetheless their use
as names of user-defined objects should be eschewed.  See fortune("dog").

You *can't* actually assign values to reserved words.  E.g.

     TRUE <- 42

throws an error.  (Whereas matrix <- 42, bad form though it may be,
does not throw an error.)

     cheers,

         Rolf Turner

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using reserved words in R, and reuse variable names in different functions

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